Efficient and clean use of fossil energy under the "double carbon" goal

China's rapid economic development is the driving force behind the rapid growth of fossil energy production and consumption. Since 2005, China has been the largest emitter of energy-related carbon dioxide (CO2). Power and industry are the main battlefields of fossil energy consumption in China, and industries such as power, steel, building materials and chemical industry have therefore become large CO2 emitters in China. Therefore, the efficient use of fossil energy is the key to achieve the goal of carbon peak and carbon neutrality (hereinafter referred to as "double carbon") in China.

China's energy and resource endowment and incompatible energy structure, complex international environment, rapid and high-quality economic and social development and the need to cope with the change of gasification and other factors require that we must unswervingly promote the energy revolution. Especially under the requirements of the "dual carbon" goal, the task of CO2 emission reduction in the medium and long term development of energy is more clear, and it is necessary to comprehensively promote the large-scale development and utilization of clean energy and build a diversified clean energy supply system. Fossil energy is still the main source of energy, which needs total control and orderly replacement. To realize the efficient, clean and low-carbon use of fossil energy is the top priority in promoting the energy revolution and transformation, and building a clean, low-carbon, safe and efficient energy system.

Current situation of fossil energy utilization in China

Coal-fired power generation technology

Since the founding of New China, with the continuous investment and support of the state, coal-fired power generation technology has made great progress, and coal-fired power generation technology and equipment continue to develop in the direction of high parameters, large capacity and low emissions. At present, China has reached the world advanced level in ultra-supercritical coal-fired power generation technology, circulating fluidized bed combustion technology, and ultra-low emission technology of conventional flue gas pollutants. The coal consumption of coal-fired power units shows a gradual decreasing trend, but the decline of coal consumption gradually slows down due to the reduction of peak load and utilization time of the units (Table 1).

Clean coal-fired power generation. After more than 10 years of development, the discharge of conventional pollutants from coal-fired power generation has been effectively controlled. By the end of 2020, China has a total of 4,990 coal power units with an installed capacity of 1.08 billion kilowatts, and more than 950 million kilowatts of coal power units have reached the ultra-low emission limit. China has built the world's largest clean coal-fired power generation system, and conventional pollutants are no longer the main constraint on coal-fired power generation, and are currently working towards a near-zero level.

Efficient coal-fired power generation. In the past few decades, coal power units have been developing towards high parameters. Advanced ultra-supercritical power generation technology is the world's main coal-fired efficient power generation technology, which includes double reheat ultra-supercritical unit and ultra-supercritical circulating fluidized bed unit. Since the Tenth Five-Year Plan, China has deployed key projects and continued to support the research and development and application of ultra-supercritical power generation technology; During the "13th Five-Year Plan" period, six secondary reheating units were put into operation successively in Anyuan, Taizhou, Laiwu, Bengbu, Suqian and Jurong, with two types of steam parameters: 31 MPa/600℃/610℃/610℃ and 31 MPa/600℃/620℃/620℃. In addition, two ultra-supercritical 660 MW circulating fluidized bed coal-fired generating units in Weihe, Guizhou Province and Binchang, Shaanxi Province were started. In 2020, ultra-supercritical units will account for 26% of the total installed capacity of active coal power units in China, of which 137 are in service with 1,000 MW grade ultra-supercritical units, with an average coal consumption of 283.59 g/kWh for the overall power supply. At present, China has accumulated rich experience in the design, manufacturing and operation of ultra-supercritical generating units, and related technologies have achieved leapfrog development: as a whole, it is synchronized with the international advanced level, and the technical indicators such as power supply coal consumption and power generation efficiency of some units have achieved world leadership, and the development speed, installed capacity and number of units have ranked first in the world.

Industrial process combustion technology

Coal combustion and utilization forms in the industrial field are mainly coal-fired industrial boilers and industrial kilns.

Coal-fired industrial boilers. There are nearly 500,000 coal-fired industrial boilers in service in China, accounting for about 20% of the country's total coal consumption. At present, China's coal-fired industrial boilers are mainly chain stokers, and the actual operation combustion efficiency and boiler thermal efficiency are about 15% lower than the international advanced level. In recent years, circulating fluidized bed boiler technology has also been well applied, forming 35 t/h, 65 t/h, 75 t/h, 130 t/h, 240 t/h steam boiler series; In addition, some pulverized coal industrial boilers have been promoted and applied in the market. Compared with the chain furnace, the thermal efficiency of circulating fluidized bed and pulverized coal industrial boilers has been greatly improved, which has been close to 90%, and the original emission level of nitrogen oxides (NOx) has also been greatly reduced. However, due to the large number of coal-fired industrial boilers, there are still problems of high overall energy consumption and heavy pollution.